1-(p-aminophenyl)-3-aminopyrazolines and process



United States Patent l-(p-AMINOPHENYD-S-AMINOPYRAZOLINES AND PROCESSRudolf Mersch, Leverkusen-Bayerwerk, and Detlef Delfs, Opladen, Germany,assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen,Germany, a corporation of Germany No Drawing. Application June 14, 1955Serial No. 515,558

' Claims priority, application Germany June 14, 1954 9 Claims. (Cl.260-310) This invention relates to novel 1-(p-aminophenyl)-3-aminopyrazolines and to a process for their production.

It is known that l-(p-acylaminophenyl)-3-aminopyrazolines (respectivelyin the tautomeric form l-(pacylaminophenyl)-3-imir1o-pyrazolidones) canbe obtained by various methods. these compounds are treated with mineralor organic acids only the 1-(p-acylaminophenyl)-3-oxypyrazolines areobtained (British Patent No. 679,678), but not thel-(p-aminophenyl)-3-aminopyrazolines.

It is an object of the present invention to provide a process for theproduction of novel l-(p-aminophenyD- 3-aminopyrazolines respectivelyl-(p-amifidphenyD-S- iminopyrazolidones froml-(p-acylaminophenyl)-3-aminopyrazolines. Further objects will appearhereinafter;

These objects are attained in accordance with the present invention byalkaline saponification of l-(p-acylaminophenyl) -3-arninopyrazolines.

The l-(p-acylaminophenyl)-3-aminopyrazolines can be obtained by usingthe methods described in British Patent No. 679,678 and in theco-pending application.

Serial No. 440,562, filed June 30, 1954, now abandoned. According to theco-pending application, these compounds are obtained by reducing afl-[N-(p-acylaminophenyl)-N-nitroso-l-aminopropionitrile; -wherein .thephenyl nucleus can be substituted by halogen or alkyl, alkoxyl,hydroxyamino, acylamino, carboxyl or sulfonic acid groups and whereinthe amino group of the'p-aminophenyl radical can be mono-substituted byan alkyl radical, at a pH ranging from 1 to 7.

Suitable compounds which can be used as starting materials are, forexample, 1-(p-aceto-methylaminopheny1)-3-aminopyrazoline,l-(p-aceto-aminophenyl) -3 -aminopyrazoline and1-(p-aceto-amino-m-chlorophenyl)-3- aminopyrazoline.

The saponification can be carried out with aqueous or concentratedalkali metal hydroxide solution or soda solution preferably at elevatedtemperature.

The 1-(p-aminophenyl)-3-amino-pyrazolines tend to decompose in the air.Therefore, preferably they are stored in form of their stable salts, forexample the dihydrochloride.

It was very surprising that the amino respectively imino group in the3-position of the pyrazoline ring of l-(p-acylaminophenyl)-3aminopyrazolines respectively 1 (p acylaminophenyl) 3 iminopyrazolidonesexhibits such a stability against the action of aqueous alkali; whilethereaction with aqueous acids results in a hydrolyzation of the abovementioned amino respectively imino group.

The l-(p-aminophenyl)-3-arninopyrazolines obtainable by the process ofthe invention are useful photographic developing agents.

The present invention is further illustrated by the following exampleswithout, in any Way, limiting it.

It is further known that if "ice 7 2 Example-1 f 23.2 grams of1-(p-aceto-methylaminophenyl)-3-aminopyrazoline (M. P. 263 C.) arerefluxed in 230 milliliters of l-normal sulfuric acidfor 4 hours.Uponcooling, the 1-(p-aceto-methylaminophenyl)-3-oxypyrazolinecrystallizes in good yieldfrom the acid solution. M. P. 198 C. Example?23.2 grams of 1-(p-aceto-methylaminophenyl)-3 -aminopyrazoline (M. P.263 C.) arerefluxed in 270 milliliters of a 10% sodium hydroxidesolution for 10 hours. Thereby, the1-(p-methylaminophenyl)-3-aminopyrazoline formed partly dissolves in thesolution while another part remains undissolved as oil. Upon coolingftheExample 3 21.8 grams of 1-(p-aceto-aminophenyl)-3-aminopyrazoline (M. P.204 C.) are refluxed with 220 milliliters of a 5% solution of sodiumhydroxide." The l-(p-aminophenyl)-3-aminopyrazoline formed. dissolves inthe solution and can be obtained upon cooling in crystals with goodyield. M. P. about 175. C. under. decomposition.

The 1-(p-aminophenyl)-3-aminopyrazoline' dihydrochloride can be obtainedby following the procedure of ExampleZ.

Example 4 20.4 grams of l-(p-formylaminophenyl)-3-aminopyrazoline (M. P.168 C.) are refluxed with 200 milliliters of a 10% soda solution for 6hours. Upon cooling, the l-(p-aminophenyl)-3-aminopyrazoline formedcrystallizes. The product obtained is identical with the one obtained inExample 3. 7

Example 5 23.2 grams of 1-(4-acetylamino-3'-methylphenyl) 3aminopyrazoline (M. P. 237 C.) are refluxed with 230 milliliters ofa 10%sodium hydroxide solution for 12 hours. Upon cooling, the1-(4'-amino-3-rnethylphenyl)- 3-aminopyrazoline formed is obtained ingood yield. M. P. about 166 C. under decomposition.

Example 6 24.8 grams of 1-(4'-acetylamino-3-methoxypheny1)-3-aminopyrazoline (M. P. 194 C.) are refluxed with 180 milliliters of a10% solution of sodium hydroxide in the presence of 2 grams of sodiumhydrosulfite and in a nitrogen atmosphere for 6 hours. The 1-( 4-amino-3'-methoxyphenyl)-3-aminopyrazoline formed is obtained upon cooling ingood yield. M. 'P. about 136 'C. under:

decomposition. V I

" Example 7 25.3 grams of 1-'(4-aceto-amin-o-3T-chlorophenyl)- presenceof '2 grams of sodium hydro'sulfite in a nitrogen atmosphere for '12hours. The 1-(4'-amino-3'-chlorophenyl)-3-aminopyrazoline formedcrystallizes upon cooling. M. P. about 189 C. underdecomposition.

p y v a 3 I.

NHR NHR Example 8 23.2 grams of1-(4'-aceto-ethylaminophenyl)-3-aminopyrazoline (M. P. 202 C.) arerefluxed with 250 milliliters of a 10% sodium hydroxide solution byfollowing theprocedure of Example 7. The l-(4-ethylamino)-3aminopyrazoline formed is obtained in good yield. M. P. about 104 C.underdecomposition.

Example p wherein R represents a' member selected frdmthe groupconsisting of hydrogen and. alkyl, and X is a member selected from thegroup consisting of hydrogen, 'alkyl, alkoityl, and halogen.

2. .Asynovel compound the compound represented by the tautomericformulae I HaC----C=NH5 H 3. As .novel compound the compound representedby the tautomeric formulae 4. As novel compoiind the compoundrepresentedby the' taut omeric formulae p on. I on."

5. As a new chemical compound, the dihydrochloride of the compoundrepresented by the tautomeric formulae H2(IJCNH2 mo N NH: NH2

6. As a new chemical compound the dihydrochloride of the compoundrepresented by the tautorneric formulae 7. A process for the productionof organic compounds represented by the tautomeric general formulae20O=NH v mc-o-mn A wherein R represents a member selected from the groupconsistingof hydrogen and alkyl and X represents a member selected fromthe group consisting of hydrogen,

alkyl', alkoxyl, and halogen, which'compn'ses subjecting to an alkalinesaponification acompound represented by the tautomeric formulae whereinAc represents an acyl radical and R and X represent radicals as definedabove, and recovering the compound formed.

8. A process for the production of a compound represented by thetautomerie formulae NE: NH,

5 which comprises subjecting to an alkaline saponification whichcomprises subjecting to an alkaline saponification a compoundrepresented by the tautomeric formulae a compound represented by thetautomeric formulae H,c--NH, HzC-(i"2=NH HaC-CNH H2C---C=NH mc N mo /NH5 Hi0 /N H,o /NH N N N N l l I l E J E 1 E 1 E NHAc NHAo CH NAe CH3NA0wherein Ac represents an acyl radical, and recovering wherein Acrepresents an acyl radical, and recovering the compound formed. thecompound formed. 7

9. A process for the production of a compound represented by thetamomenc formulae References Cited in the file of this patent f= UNITEDSTATES PATENTS H10 NH 2,726,248 Kendall et al. May 11, 1954 i FOREIGNPATENTS 679,678 Great Britain Sept. 24, 1952 OTHER REFERENCES Karrer:Org. Chem. (Elsevier, 2nd Eng. Ed.), p.

Nnem Nrrcn. 452 (1946).

1. AS A NEW CHEMICAL COMPOUND, A MEMBER SELECTED FROM THE GROUPCONSISTING OF THE FREE BASES AND THEIR SALTS COMPOUNDS HAVING THETAUTOMERIC GENERAL FORMULAE